1. Field of the Invention
This invention pertains to a two-way check valve, such that air flow from an air space is through a first passageway, while air flow to the air space is through a second passageway. The first and second passageways include openings which are selectively sealed by O-rings.
2. Description of the Prior Art
In the prior art, flow limiters or check valves have been provided which are unidirectional. The bi-directional check valves and flow limiters, as well as many of the unidirectional check valves and flow limiters, have tended to have a complicated structure with attendant high manufacturing and maintenance costs. Moreover, some of these devices have not sealed the moment the plunger stopped moving and have not satisfactorily provided for consistency of performance due to the reliance on the dynamic movement of the lip seal. Similarly, many of these devices have not been self-cleaning thereby further increasing the maintenance costs.
Moreover, in the prior art, damping action can be dependent on the lip seal seating against the face of the plunger consistently. This action can be prone to gathering lubricants, debris and moisture caught in the "sandwiching" action. Moreover, a linear action must occur to move the lip seal from a sealed position to an unsealed position.
Representative prior art includes U.S. Pat. No. 5,762,10.3 entitled "Tilting O-Ring Check Valve" issued on Jun. 9, 1998 to Gregoire; U.S. Pat. No. 5,660,205 entitled "One-Way Valve" issued on Aug. 26, 1997 to Epstein; U.S. Pat. No. 5,126,722 entitled "Point of Lube Monitor" issued on Jun. 30, 1992 to Kamis; U.S. Pat. No. 4,549,565 entitled "Reclosing Rupture Disk Assembly" issued on Oct. 29, 1985 to Short, III; U.S. Pat. No. 4,497,749 entitled "Check Valve for Ammonia Injector Apparatus" issued on Feb. 5, 1985 to Strauss; U.S. Pat. No. 4,428,566 entitled "Two-Tube Hydropneumatic Shock Absorber" issued on Jan. 31, 1984 to de Baan et al.; U.S. Pat. No. 4,237,935 entitled "Hydraulic Pressure Relief Valve and Fluid Isolator" issued on Dec. 9, 1980 to Delmonte et al.; U.S. Pat. No. 4,214,607 entitled "Unidirectional Flow Limiter" issued on Jul. 29, 1980 to Bouteille; and U.S. Pat. No. 4,111,228 entitled "Respiratory Valve, Especially for Anaesthetic Circuits" issued on Sep. 5, 1978 to Simionescu.